Mineral oil compositions and methods of suppressing foaming in oils



Patented Mar. 26, 1946 UNITED STATES- 1 PATENT ,orrics MINERAL OIL COMPOSITIONS AND METH- ODS OF SUPPRESSING FOAM ING 1N OILS Herschel G. Smith, 'Wallingford, and Troy L. Cantrell, Lansdowne, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., a corporation of Pennsylvania No Drawing.

. Application August 11, 1942, Serial No. 454,469

by the churning of the gears gives rise to excessive leakage and loss of lubricant past retainer rings, etc. Moreover, foaming seriously interferes with the proper functioning of the oil. Automobile gears such as those used in transmission and diiferential gear assemblies'often operate at very high speeds, as well as under high tooth pr'es-* sures: therefore they require a very good lubrlcant to prevent or retard excessive wear due to metal-to-metal contact, and foaming is undesirable. The lubricants employed are viscous oils,

often containing a so-called extreme pressure agent to assist in maintaining an oil film between the teeth; sulfurized sperm oil being especially good. If the lubricant contains air dispersed through it, it lacks proper film forming properties. Moreover, foaming oil is much less effective to conduct heat away from the working zone.

These dlmculties are often aggravated by the fact that some extreme pressure agents present in the oil actually increase the foaming characteristics of the oil composition.

Foaming is also objectionable in other situations; for example, during the pumping of oils, and in compounding oils with extreme pressure agents and other additives-an operation involving thorough agitation. Nearly all petroleum oils foam to some extent under violent agitation; the more viscous the oil the greater the amountof foam and the longer it persists after agitation is stopped.

Among the objects of our invention are the provision of a method whereby foaming or frothing of oils as described is suppressed; and the provision of gear lubricants and other'lubricating compositions which are characterized by freedom from tendency to foam or froth even under severe conditions.

. We have discovered that foaming of petroleum oils, even under. the most violent conditions described, can be suppressedor prevented, by incorporating in the mineral oil a small proportion of quinoline isoamyl octyl phosphate.

In general, dissolving almost any additive agent-in oil has a tendency to increase foamingmore or less. This compound is remarkable in that it suppresses foaming. even when-present in small amounts. It has no deleterious effect on the lubricant properties or other properties of the 011.

- This agent can be incorporated in all sorts,

of;oils, to achieve the stated results. One particularly advantageous field of use is in gear lubricants for automobiles and the like. vAs

1ov stated, these lubricants are viscous and they con- I tain' extreme pressure agents or other additives; both of which facts make for heavy foaming. By dissolving a fraction of a per cent of our agent in the lubricant foaming is prevented. For

15 example, such a gear lubricant, within the purview of our invention, ihas-the following composition (per cent by weight):

Refined high-viscosity, lubricating oil..- 89 to 95 Refined sulfurized sperm oiL'. to

Quinolineisoamyl octyl phosphate--- 0.01 to 1.0

Another field of use is in'light (low viscosity) oils used in so-called fluid drives or in hydraulic drives. With these light oils (which are often of viscosity as low as SAE 10 grade) agitation 80 as 'a lubricant or not. in which it is desired toprevent foaming.

In preparing the new agent, quinoline is brought into reaction with isoamyl octyl acid ortho phosphate, and the pH of the reaction mixture is adjusted to within the range 2.0 to 5.5, V

with the theoretical molecular ratio of the two reactants, namely 1:1, the product is apt to be slightly too acid, with a pH below 2, and this is taken care of by using a slight excess of the quin- 40 Aoline, or by adjustment with a suitable amount of I another characteristic amine, so that the molecular ratio is between 1:1 and 1:1.1, or equivalent. The reaction product is an oily liquid. It readily dissolves in oils or oil compositions.

The proportion of the agent to be dissolved in the oil or oil base depends on the viscosity of the oil, its ingredients and the severity of the conditions of use. Ordinarily 0.01 to 1.0 per cent of the agent by weight of the oil is employed; the quincline isoamyl octyl phosphate being a very efiective agent for the present purposes. 01. course, higher percentages can be used, if desired. for especially severe conditions, which ordinarily produce large volumes of foam.

Isoamyl octyl ortho phosphate is a brown, oily 2 v I asa'nsvs 1 liquid. Its specific gravity is 1.009 at 24/4 C. and its viscosity 210, '75 and 29 centipoises at 25, 50 and 75 C. respectively. It is insoluble in water and soluble in mineral oils to the extent of 11.70

part in 100 parts of oil at 20? C. The ortho phosphate decomposes at 302 to 311 F. It: has the structural formula:

mo Hell n c 't Heb Quinoline is a tertiary amine and is a colorless to yellow liquid. It absorbs water from theair and has a characteristic odor. It has a specific l gravity of 1.093, a boiling point of 237.7" C., a melting point of 22.6 C. Itsmolecular weight is 129.15. It is solubleinwater, alcohol, ether and carbon-bisulfide. It has the following formula:

Our preparation, the reaction product of the above, has the probable formula:

The following example illustrates one advantageous way of preparing our foam suppressor:

Example I.One hundred and twenty-nine 4 pounds of quinoline were added to an iron vessel equipped with an air lance and 281 pounds of isoamyl octyl ortho phosphate were introduced over a period of one hour; the slow rate of addition being desirable to maintain the temperature so of the reaction mixture below 212 F. At the conclusion of this reaction, the-temperature was 180 F. and the pH of the mixture was 2. A pH of 3.5

' was desired; 13 pounds of quinoline were added,

which brought the pH to 3.5. The reaction product 'was an oily liquid. It was readily soluble in mineral oils. Quinoline isoamyl octyl phosphate is a new chemical compound-which is claimed per se in our copending application, Serial No.

640,666, filed on January 11, 1946, as a continuaso tion-in-part of the present application.

As the quinoline isoamyl octyl phosphate is I substantially insoluble in water, the pH equivalent .is measured by the following expedient.

Normal butanol (which contains a small amount 05 ple in water, so to speak.

It will be noted that the measured pH of the amino "phosphate is low despite-the fact that a slight excess of amine is present. This is because cerned, the order of addition makes no difference.

t t Y 12 I I at c o g The butanol appears to 70 the reaction involves neutralizing a rather strong acid with a very weak base.

Moreover, traces of mono-, diand tribasic acids may be formed under the conditions of the pH determination. At any rate, the results are as stated.

The following example illustrate the preparation of a gear lubricant in accordance with the invention.

Example II.-A highly viscous, highly refined I Pennsylvania oil was selected as the base, and in it was dissolved 0.04 per. cent of the oil reaction product of Example I. As shown in the following table the change in viscosity and in color by incorporation of the agent was negligible.-

Straight oil Improved oil Composition Gravity, "API 26. 5 26. 4 Viscosity SUV: 100 1,907 1.894 210 F.-..- 140.1 140. 4 Color, NPA 4. 4. 75

To evaluate the foaming properties of the straight oil and the improved oil, samples (500 cc.) of the two oils were subjected to foam test No. 1 (described below). The results 'were as follows: v

Composition Straight oil improved 011' At end of stirring 15 minutes):

Temperature, F s4 83 Volume of oil and (cam, 00.. 1, 766 540 1 3. 51 1. 08

' 11 11 670' 500 l. 84 l. 0 Fine No loam volume of oil and foam Raw) of volume 0? original oil of foam remained even after an hour standing; Y while the improved oil developed only a negligible amount of foam, which was all gone at the end of an hour.

Decreasing the percentage to 0.01 still leaves the oil much less susceptible to foaming than the straight oil.

The foam' suppressor as stated can be added to compounded lubricants to prevent foaming thereof. It is compatible with most of the other types of improvement agents now employed and the amount required to prevent foaming in such compounded lubricants is relatively small-and does not deleterlously affect the other properties of compounded lubricants.- This is an important part of the invention, as certain of the agents employed to impart particular properties to lubrieating oils have been found alsov topromote the foaming of the oil composition when agitated. By adding even traces of the present foam suppressor, such compounded lubricants become veryv resistant to foaming, even under drastic service conditions.

In making up compounded lubricants of this type it is advantageous to dissolve the amino phosphate in the oil first, as thereby foaming is prevented during the step of mixing in the extreme pressure agent or other additive.- But so far as performance of the lubricant in service is con- The following example illustrates the properties of an extreme pressure gear lubricant prepared in accordance with the invention.

Example III.-A modern gear lubricant containing 92.0 per cent by volume of a highly refined Pennsylvania oil and 8.0 per cent of a special synthetic mixture containing around per cent sulfur. A similar lubricant prepared according to the invention contains these oils in the proportions of 92.0 per cent and 8.0 per cent respectively, and 0.04 per cent of quinoline isoamyl octyl phosphate. The viscosity of the modern lubricant was 1918 SUV at 100 F., 767 at 130 F. and 141 at 210 F. The viscosity of the improved lubricant was only negligibly different from-this, and the same was true of'the ,other characteristics-:- gravity, viscosity index, flash and fire tests, pour test, color, sulfur, copper strip tests, centrifuge test (for gravity-separable matter), and carbon residue. The neutralization number of the new lubricant was 0.56 against 0.50 for the old. The surface tensions were nearly identical. The Almen and Timken tests, indicative of the lubricatlng value of the oil, as secured on the compounded oil before the addition of the foam suppressing agent, were the same as the correspondthe type indicated and being so positioned with respect to each other that the two pairs of beater elements are at right angles and rotate in opposite directions in closely spaced, overlapping mg tests made after the addition of the indicated amount of this foam suppressor.

In other words, the characteristics of the two lubricants were practically the same-except for the foaming properties. The following are comparable tests (the nature of which is described in detail below) on these properties. The samples were 500cc. each, the speed of the agitators 550 R. P. M and the initial temperature 77 F.

Foam tests gag? New lubricant AMI stirring for winin" us min 44 hr.

Temperature, F 84 83. ill-l-fgarlrli, (i0 1,750.... ,535. 595. W 3.50. 1.07..... 1.19. Alter1 standing 1 hr. after stirring stoplemperature, F 77 0il+foam, cc.-..- 500. Vol. of oll-Hoam 1 00 ,Vol. of oil Nature of foam Fine. None-.. None.

tendency of the oil to foam and the stability or permanency of the foam produced. In general it resembles a somewhat similar testing method employed by the General Motors Corporation for determining the foaming tendencies of gearing lubricants, but has been modified in the direction of greater accuracy and in order to make it possible to record more comprehensible test data.

Foaming test (No. 1) -A n agitating means is provided which is an adaptation of an ordinary commercial motordriven household mlxera Sunbeam Mixmaster, Model 1, manufactured by the Flexible Shaft Company, Chicago, Ill. The device employed in the test is the usual household model with two slight changes: the turntable of the usual household model mixer is replaced by a rigid platform,

paths. In operating position, the heaters are perpendicular to the base of the mixer, as shown in Patent 2,161,881. In the present test they are centered in the container, and the bottom of the heaters is spaced approximately 1%; inch from the bottom of the pan when the latter is, positioned on the rigid platform. With 500 cc. of oil in the container, the heaters are submerged in the initial oil sample only to a depth of A of one inch. The heaters are rotated at aspeed of 550 R. P. M. controlled within :10 R. P. M.

A measured sample of 500 cc. (:5 cc.) of oil is introduced into the container, the temperature of the sample is brought to 77 F., and the container is then placed in position and the beater elements lowered into operating position,

The motor is started and adjusted to the speed indicated above. The boaters agitate theoil and beat air into the sample. Agitation is continued for exactly 15 minutes. V

The motor is now stopped, the heaters are removed from the oil, and any oil or foam adhering to the heaters is permitted to drain into the container, which takes one or two minutes. The foam level is then immediately determined, and the temperature of the sample is measured. It is then possible to calculate the ratio of the volume of oil and foam to the volume of the original oil, .with correction for any temperature changes.

The container is removed and allowed to stand quiet for one hour (measured from the time stir,- ring is stopped). The volume and temperature measurements are taken again, and serve to indicate stability or permanence of the foam produced. I

The test procedure may of course be varied, as

for example by changing the size of the sample,

' appears very quickly when agitation is stopped.

These conditions are found, for example, in marime turbine lubrication systems (which use light oils) at the point where returned 011 is discharged violently into a reservoir. To evaluate foaming in such cases there is employed a third test, No. 3. similar in all respects to tests No. 1 except that the measurements of oil and foam are made while the motor is still running. The following example shows how a turbine oil treated according to the invention behaves under such conditions.

Example 1v.-s highly refined Pennsylvania turbine oil was subie ctedto test No. 3. After 15 800 cc.-, as compared with 500 cc. for the original oil. The same oil after treating with 0.01% quinoline isoamyl octyl phosphate showed only 535 cc. of 011 plus foam.

While our invention has been described above with reference to various specific examples and embodiments, it will be understood that the invention is not limited to such illustrative exam, pies and embodiments, but may be variously practiced within the scope of theclaims herein made.

What we claim is: 1 1. A mineral oil composition resistant to'ioam ing, comprising mineral oil and 0.01 to 1.0 per cent of. quinoline isoamyl weight of the oil.

2. The composition of claim minutes agitation. the oil plus roam measured product or quinoline and an isoemyl octy'l orthophosphate having the following formula:

between 2.0 and 5.5.

3. A gear lubricant comprising a viscous minerali'lubricating oil, sulturized sperm, oil, and a small amount 01 quinoline isoamyl ,octyl phosphate, the proportion of said phosphate being suflicient to prevent roaming and varying from octyl phosphate by 15 0.01 to 1.0 per cent by weighton the mineral oil.

7 wherelnthe said quinoline isoamyl octyl phosphate is. a reaction mscmasmm. morhcm'mmr. 

